Air bypass screws way off from each other - '00 1150GS

Discussion in 'GS Boxers' started by Jazz62, Apr 7, 2012.

  1. Jazz62

    Jazz62 Long timer

    Joined:
    Oct 5, 2009
    Oddometer:
    1,081
    Location:
    Midwest
    Got Grok's most excellent Harmonizer a few days ago. (can be found here in the Vendors section):

    http://advrider.com/forums/showthread.php?t=701625 (no affiliation with Grok etc)

    Finally got a chance to play with it today. My new to me '00 1150GS seems to run pretty good but coming from my lumpy and temperamental Multistrada I may be too easy to please. Before hooking up the Harmonizer I checked the position of the big brass air bypass screws. To my surprise the right side was fully seated all the way clockwise, the left side was 2 1/2 turns out from seated. I got the bike warmed up to two bars, turned her off and hooked up the Harmonizer. Started her up and the reading was pretty close to zero, about -18Mbar, BMW spec is +/- 25Mbar. Idle is not rock steady, hovering around 1100-1150. I know there's a lot of things at play here but the valve adjustment was done (by previous owner) less than 500 miles ago, new throttle cables installed around the same time. I turned the bike off and listened to the throttle plates clack closed a few times while twisting the throttle and releasing quickly. I know this is a crude technique but I only heard one simultaneous clack telling me they are at least mechanically in sync. What conditions could exist that would have these air screws set so different from each other. I know this is opening a can of worms but I'm a noob mechanic that needs to learn.

    Ron
    Chicago
    #1
  2. PaulRS

    PaulRS Dutch fool

    Joined:
    Apr 15, 2008
    Oddometer:
    830
    Location:
    Holland, land of tulips and wooden shoes
    Start by taking them Big Brass Screws (BBS) out and clean the tips and holes.
    Count the number of turns it takes to bottom, that's your starting point.

    Once clean and refitted to that starting point, hook up the harmonizer and check.
    With a bit of luck you can get an equal reading by turning one bbs in and the other one out, but they should be within 1/2-1 turn from each other. Less is more here.

    If not, set both bbs at 2-1/2 turns out and equalize with the 'forbidden' screw on the rhs cablepully.

    Paul.
    #2
  3. ragtoplvr

    ragtoplvr Long timer

    Joined:
    Oct 18, 2007
    Oddometer:
    6,859
    Location:
    central USA
    Ron, please list the miles on the bike, here are things that happen with the miles. Cleaning the BBS and throttle body is a good first step. I take the throttle body loose, not off, just loose and clean the BBS, passage and around the throttle plate with spray cleaner. I do not like the cleaner gunk going into the engine. That normally fixes the problems. Use lots of rags, some of the cleaner will stain engine paint. Lots of bad stuff in gas anymore. The throttle bushing and shaft can wear at high miles, the best fix is rebuilding, you probably do not have that problem. If you do, it is not real expensive to fix, no big deal.

    An idle that varies about 50 to 100 RPM, with a slight stumble at the lowest RPM at about a 1 or 2 second rate is common and due to the emission control, the O2 sensor only reads a narrow range, so the moronic always varies the mixture from slightly rich to slightly lean so the sensor crosses it's reading range. During the lean excursion there is often a slight stumble. Around 2 temp bars on the RID the system goes into this mode, and I can feel it. As the engine warms more, it tolerates the lean mixture more and the stumble becomes less.

    Rod
    #3
  4. Jazz62

    Jazz62 Long timer

    Joined:
    Oct 5, 2009
    Oddometer:
    1,081
    Location:
    Midwest
    The bike has 65K. Is the forbidden screw truly forbidden? I will back the BBS all the way out and clean it up. I thought about doing that but wasn't sure if it were possible to remove it without completely ruining something.
    #4
  5. BeamingBeagle

    BeamingBeagle n00btube

    Joined:
    Oct 5, 2011
    Oddometer:
    87
    Location:
    Los Angeles
    I have an '01 and everything you're saying about the way the bike runs sounds fine. BUT the bbs should be closer to each other.

    I would also point your attention to the valve adjustment. Make sure gap clearance is as close as you can get it and readjust the TBS's. I'm not an experpert by any means but I've done this procedure 3 times now. The better I've adjusted the valves the closer those screws seem to get.:D
    #5
  6. Jazz62

    Jazz62 Long timer

    Joined:
    Oct 5, 2009
    Oddometer:
    1,081
    Location:
    Midwest
    Okay, so I removed both BBS and cleaned them very well. The o-rings were in their proper grooves on the BBS when removed. When I attempted to install the BBS it shredded the o-ring completely :eek1
    I don't understand how this could happen. I was very careful in aligning the BBS when inserting it. What the hell do I do now? Can these o-rings be found at my local Home Depot or auto parts store? Of course I was stupid enough to shred both of them. So when re-installing the BBS is the rubber o-ring supposed to be inserted into the hole first then insert the BBS.

    Edit - just looked at Max BMW parts fiche and it does not show that there is an o-ring on the BBS screw - wtf?
    #6
  7. tagesk

    tagesk Tuscan rider

    Joined:
    Jun 23, 2007
    Oddometer:
    3,230
    Location:
    Tuscany, Italy
    First of all: Some first aid.
    Get yourself a Gin Martini, possibly a (very) dry one.

    With that in hand, you will be (even more) relieved to hear that it is a standard O-ring.
    Bring the screw to any hardware store and they'll find you a new one.
    The O-ring attaches to te screw, not into the hole.

    Then, some theory (which will sink in without resistance as you have now made yourself a second (dry) Martini).

    Those screws are for very fine tuning of the air-flow when the throttle bodies are "closed":
    I write "closed" since they don't close completely; a sliver of air is let through.
    Or, in other words: Those screws are (only) used to ensure you can get the bike to idle perfectly.
    No vibrartions, and at about 1100 RPM.

    If you screw them "more or less" to the same depth your bike will run just fine.
    Although possibly not at idle.

    If you have vibrations below, say, 5000 RPM, you need to look carefully at the wires (and not the screws).

    Better now?

    [TaSK]
    #7
  8. tagesk

    tagesk Tuscan rider

    Joined:
    Jun 23, 2007
    Oddometer:
    3,230
    Location:
    Tuscany, Italy
    On the other hand....those screws are the very last thing you check.
    You have checked the valves (.15 and .30) and sparks - yes?
    Then that there is 1mm slack on the wires on both sides - yes?
    And you are convinced that when you close the throttle, you hear both bodies "click" close simultaneous - yes?

    After checking that, I always balance the throttles at (about) 2.500 or 3000 RPM.
    Then I do the idle with the screws at the very end.

    Just checking, you know.

    [TaSK]
    #8
  9. Jazz62

    Jazz62 Long timer

    Joined:
    Oct 5, 2009
    Oddometer:
    1,081
    Location:
    Midwest
    Tagesk - you are very funny indeed. I have one major problem with your advice, I don't drink. Yes, I know this is somehow some major shortcoming of my personality, especially for a jazz musician. Upon closer inspection of the throttle stops I noticed that the left side "sacred" screw doesn't make contact with anything at fully closed position. In the place where it should make contact with something there is just a round hole. The right side "sacred" screw definitely makes solid contact with this same place. The only difference I can see is that on the right side where the left side there is a round hole, the right side has a solid area. Sorry for the piss poor descriptions. Maybe I should try to post a couple of photos. I am relieved that I can source the o-ring easily. What I don't understand is why did the o-ring shred when trying to re-install the BBS? I was careful with it. Does the o-ring need a little silicone grease applied to it first or did I damage the o-ring by allowing to remain on the BBS while it was soaking in the carb cleaner? Also, this is great information to finally understand that the BBS only affect fine tuning at idle. I did not realize this from all that I've read so far.

    Note to self: start drinking :freaky
    #9
  10. tagesk

    tagesk Tuscan rider

    Joined:
    Jun 23, 2007
    Oddometer:
    3,230
    Location:
    Tuscany, Italy
    The screw is fixed and points backward (on both sides).
    On the thing that turns when you twist the throttle, there is a "stud" that the should rest on the screw then the cable is not pulled.

    Fix that first!

    How are you going to obtain a proper jazz-esque vice like Luis Armstrong if you don't smoke too much and drink Dry Martinis? :lol3

    [TaSK]
    #10
  11. ragtoplvr

    ragtoplvr Long timer

    Joined:
    Oct 18, 2007
    Oddometer:
    6,859
    Location:
    central USA
    No silicone grease, it poisons the O2 sensor. You want a viton oring, any auto parts store should have them. Just a dab of oil on it.

    Second, the sacred screw seats on a hardened steel button pressed in the steel stamping for the throttle arm. If you have a round hole, yours fell out and this is the root cause. You should see the button on the other side. The throttle plates should not be resting on the bore of the throttle body, they will scar it up.

    This needs fixed. never heard of that happening. I suspect you need a good used or new throttle body now.

    Rod
    #11
  12. Jazz62

    Jazz62 Long timer

    Joined:
    Oct 5, 2009
    Oddometer:
    1,081
    Location:
    Midwest
    Here is a pic of the left side (looking down and towards front of bike), you can see the hole and there is no contact with the screw. The right side was impossible to photograph but there is a solid piece instead of the hole and the screw definitely makes contact with it at fully closed position. Jesus Christ, really a new throttle body???!!! Let's see hmm, $450 for a new throttle body or a one-way ticket to Milan...Tagesk, you better make me something strong to drink!

    [​IMG]
    Throttle pulley by piano62, on Flickr
    #12
  13. ragtoplvr

    ragtoplvr Long timer

    Joined:
    Oct 18, 2007
    Oddometer:
    6,859
    Location:
    central USA
    You can even see the witness marks where the button used to be. I would see about getting a screw the right size, file down the head a bit and put a nut on the backside with liberal locktite. Or see a machinist and have him make you a piece to put in there, that would be much less than $450. When you have the throttle body off for the work, you can evaluate if the bore is badly damaged.

    If so then used is your best bet

    Now something else to worry about, where did I put my BMW worry beads.

    Rod
    #13
  14. Jazz62

    Jazz62 Long timer

    Joined:
    Oct 5, 2009
    Oddometer:
    1,081
    Location:
    Midwest
    There must be something that can be used in place of whatever is there normally without having to replace the entire throttle body. The piece that should be there is some type of press fit thing, almost like a rivet, right? I feel my creative juices starting to flow which is good to counteract the acid in my stomach. What do you mean when you say the "bore" and how would it be damaged by this stud missing?
    #14
  15. tagesk

    tagesk Tuscan rider

    Joined:
    Jun 23, 2007
    Oddometer:
    3,230
    Location:
    Tuscany, Italy
    Find as small bolt and make the head as thick as the "stud" on the other side.
    At least I would have tried that first.

    Unless you happens to be Miles Davies and 450USD is nothing.

    They don't need to be exactly equal - you have the brass screw to compensate for some small difference.

    [TaSK]
    #15
  16. ragtoplvr

    ragtoplvr Long timer

    Joined:
    Oct 18, 2007
    Oddometer:
    6,859
    Location:
    central USA
    The area inside the throttle body where the throttle plate is located. The magic screw makes sure the brass throttle plate does not hit the aluminum bore, when the plug fell out that is what started happening.

    Brass can wear the aluminum, make balance difficult. You can look.

    Best is to make a replacement now and stop any further damage. Set both clean BBS to 2.5 turns, and see if you can set the magic screw to balance things pretty close.

    Rod
    #16
  17. SpaceManSpiff

    SpaceManSpiff Man of Mystery

    Joined:
    Mar 13, 2007
    Oddometer:
    1,075
    Location:
    Tucson, Arizona
    Jazz,

    here is a pic of the RH throttle stop on my 2001 R1100S (should be the same TB as your GS).
    [​IMG][/url][/IMG]

    My guess is that is a threaded 2 piece affair...but it doesn't seem to be listed separately on the parts microfiche.
    http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51759&rnd=04052012
    not on the Throttle Housing Assy fiche or the one with the Bowden box and associated cables anyway.

    It is a bit of a bummer that the missing throttle stop is on the left (TPS) side...you will probably need to do a zero-zero to get back to a good base setting. That the throttle stop is missing and that the BBAS are at wildly different setting is telling me that the something funny is going on....

    On the topic of BBAS O-rings (I just went through a quest to to find these for this on my R1100S)--
    Like my bike, your GS bike uses the M9x0.75 BAS (not all oilheads use a BAS this size).
    The o-rings are a metric size 1.5mm (cross-section) x 7.5mm (I.D.)

    The o-rings are not available separately from BMW. The BAS is available from BMW ($6+) and may come with the BAS...but curiously are not shown on the microfiche.

    Unlike others, I found that the nearest standard sized o-ring available at hardware and autopart stores (5/16" (7.65mm) I.D. with a 1/16" (1.78mm) C.S. did not fit to my satisfaction. Either the C.S. is too big or the durometer of the rubber is too hard...but it wanted to jam with too many turns out.

    Bing (who makes the throttle body) sells the o-rings for about $2.50 ea.
    http://www.bingcarburetor.com/pdf/throttlebodykits.pdf

    amazon has a pack of 25 viton o-rings for $6.32
    http://www.amazon.com/M1-5x7-5-Viton-O-Ring-Shore-Durometer/dp/B005RUPENG

    HTH
    #17
  18. PaulRS

    PaulRS Dutch fool

    Joined:
    Apr 15, 2008
    Oddometer:
    830
    Location:
    Holland, land of tulips and wooden shoes
    That stop is a push-in button with a serrated shaft, hence the markings in the hole.

    Any suitable bolt/nut, or rivet will do as a replacement.
    Whatever you put in there, make sure the surface on which the forbidden screw sits is the same height as the one where the button is still present.

    If required, I'll snap some pic's and measurements from a cable pulley I have laying around.

    Paul.
    #18
  19. GS Addict

    GS Addict Pepperfool

    Joined:
    Sep 24, 2006
    Oddometer:
    4,276
    Location:
    Sunshine Coast B.C.
    I have a spare set of tb's
    I will go downstairs and mike the height the "button". That will allow you to get close with the bolt and nut mod.
    Stand by...............

    OK I'm back
    It is a press fit button that can easily be replaced by an 8-32 x 3/8 screw and nut on the other side.
    Head diameter needs to be .272" and the head height needs to be.083" high.
    I got these measurements off 3 different bodies.

    If you do not have the resources to make one up I can make you one up for the cost of shipping
    #19
  20. SpaceManSpiff

    SpaceManSpiff Man of Mystery

    Joined:
    Mar 13, 2007
    Oddometer:
    1,075
    Location:
    Tucson, Arizona
    @PaulRS --thanks I didn't know that...thanks (sure looks like that from the marks).

    @GS Addict --good work!

    This should help the OP get back on the road.
    #20